No Problem when:+ powered USB hub between PC and sound card "sound OK" ( "bad sound" without power )+ The REALLY WEIRD: if I increase CPU usage, e.g. if I move a window in Windows continuously the output is OK

Could it be due to the USB power? (Not yet measured)I've read that some USB devices could damage PC. "This could, in extreme cases damage the USB port on the host or upset the energy management of the computer, which can lead to unstable behavior."Possible? While yes: enough to measure only via Soft-PC-Diagn.Tool e.g. SpeedFan? Or do I have to measure with a MultiMeter?

Could it be speed of USB?My PC has USB2.0, however I have not found out about whether "Hi-Speed" or "Full Speed"

What ever could it be???

Am glad to rest every tip, even to the other proposals in which forum should be posted!Thank youReselty